The representative of Pope Francis in the US led a cross-border Mass on Sunday in an effort to bring awareness to the plight of immigrants and refugees.

Archbishop Christophe Pierre, the Apostolic Nuncio to the United States, was the principal celebrant as the 3pm Mass got underway in both Nogales, Arizona and Nogales, Mexico.

At least 250 people showed up on the Arizona side, said Steff Koeneman, spokeswoman for the Diocese of Tucson.

It wasn’t immediately clear how many came on the Mexico side. An altar was erected on both sides of the border.

Some sat in camping chairs or held umbrellas while listening to the Mass in 80-degree weather.

The Mass is the third one along the Arizona-Mexico border this year and is organised by Dioceses Without Borders, a group composed of church leaders from around Arizona and the Mexican border state of Sonora.

Diocese of Tucson Bishop Gerald Kicanas says the Mass focused on immigration, a major issue for the church.

Pope Francis has been outspoken in favour of immigration reform and humane treatment of migrants. Prayers were said for Border Patrol agents and others who work around the border.

“His decision to join us is a reminder that this is an issue very important to our Holy Father,” Bishop Kicanas said of Pierre’s attendance.

Past border Masses have included the delivery of communion through the fence that divides the US and Mexico, but that wasn’t be the case this time because the Border Patrol won’t allow it, church leaders say. The Masses in the past have drawn thousands.

Bishop Kicanas says the Mass was also organised to highlight the close relationship between the Diocese of Tucson and the recently founded Nogales, Sonora, diocese.

But the primary focus is to bring attention to immigrants and refugees, Bishop Kicanas said.

“The economic migrant is not a criminal. The economic migrant is someone seeking a decent way of life for themselves, for their family,” Bishop Kicanas said.

The church has been vocal in its support of migrants. When Pope Francis visited Mexico early this year, he gave a special blessing to migrant families along the border in Ciudad Juarez.

Francis stood on a specially built platform next to the Rio Grande, which separates the two countries, and offered a silent prayer for thousands of immigrants who died while trying to reach America.